Personal computers have internal power supplies which convert the AC line voltage (120VAC, 60 Hz, as commonly found in the United States) to the appropriate DC voltage levels required for the operation of the microprocessor and associated components of the computer. Some of the peripheral components of a personal computing system, such as the monitor, printer or plotter run off the AC mains either directly or from a feed-through path from a plug located on the back of the personal computer. Although there are a wide variety of personal computers in use, the vast majority of them use the aforementioned concept for powering a personal computer system.
AC power loss in the aforementioned computing environment results in a near-instantaneous loss of data and programs running on the personal computer system at the time. Moreover, loss of AC power can sometimes result in damage to some of the components such as disk drives, etc. Even momentary loss of AC power for less than one cycle of the line current can result in loss of data or incorrect results due to the power line "glitch". Also, AC power loss means the loss of AC-powered peripheral components such as monitors, printers, etc. Many prior art power supplies for personal computers simply provide a feed-through from the AC mains to a plug on the back to provide AC power to run the auxiliary or peripheral devices.
Uninterruptible power supplies are known in the prior art for providing power to computers, however they are neither efficient nor integrated in their design to obtain a compactness of design which allow them to be internally installed inside existing personal computer cabinets. Prior art uninterruptible supplies require large battery packs to source power for a short period of time due to their inefficient design and power conversion techniques. Therefore, a great need exists in the personal computing industry for a power supply that is immune to temporary interruptions of AC mains, is highly efficient for operating from batteries, provides uninterrupted AC power for peripherals, and is compact enough to fit within the housings of existing personal computers.